Introduction: The inscription of Rabatak was found in 1993 near an ancient hill in the north part of Baghlan in Afghanistan. The village of Rabatak is situated at the kilometer forty in the north-western part of the ancient province of Sorkh-Kotal near the border between Baghlan and Samangan provinces. The Rabatak inscription includes 23 lines in Bactrian language and a Greco- Bactrian script. The Bactrian language is one of the Eastern Middle Iranian Languages. It was spoken by the people of northern part of Afghanistan. It is noteworthy that Bactrian is the only Middle Iranian language whose writing system is based on the Greek alphabet, a fact ultimately attributable to Alexander’s conquest of Bactria and to maintenance of Greek rule for some 200 years after his death (323B.C.). In spite of the invasion of Bacteria by Alexander of Macedonia and his successors the Bactrian language continued to be in use.Around the Middle of the second century B.C. Bactria was overrun by nomads from the north called Tokharoi. They settled in northern part of Afghanistan and later gave their name to the area (Tokharistan). The Kushan Empire was founded early in the Christian era by Kujula Kadphises whose tribe obtained supremacy over the Tokharoi. With the collapse of the Kushan dynasty their lands fell into the hand of the Sasanians, under whom the administration of these provinces was entrusted to a governor styled Kušānšāh. From the middle of the fourth century Bactria and northwestern India were overrun by Hunnish tribes, of whom the Hephtahalites proved the most durable, maintaining their rule in parts of Afghanistan up to the Arab conquest in the seventh century. The aim of this article is to throw a new light both an the Bactrian history and language through Rabatak inscription by presenting its transliteration, transcription and translation into Persian language following The Journal of Teaching Language Skills (JTLS) 102 with a commentary and an etymological word list. It is worth mentioning that in this study the historical and linguistic points are examined. Method of ResearchI have examined the Bactrian inscription of Rabatak according to the reading and interpreting of Nicholas Sims-Williams from University of London whose reading is based on the original copies and the photograph prepared by British Museum. I have used the method of translation and transcription used by him in his several editions of Bactrian documents as well as his edition of Bactrian Legal and Economical Documents.Result: The result of studying Rabatak inscription indicates that Kanishka the great, who was the ruler of Kushan Empire, obtained his kingship from Nana and from all the gods. He discontinued the use of Greek language to be replaced by the Aryan language. In fact, any of the Indo-European languages of Iran or India could be called “Aryan”; but we are now sure that when he mentions the Aryan language, he means Bactrian, the language of his inscription, just as Darius meant Old Persian, the language of his inscription, when he wrote: “By the favor of Ahuramazda, I made another text in Aryan”.He also announced the beginning of a new era starting with the year 1 of his reign. Kanishka’s era was used as a calendar reference by the Kushans for about a century, until the decline of the Kushan dynasty. The inscription mentions the chief cities of north India which were controled by Kanishka. Conclusion: The Rabatak inscription is written on a rock in the Bactrian language and the Greek script. It was found in 1993 at the site of Rabatak, in Afghanistan. According to this inscription Kanishka the great was a righteous and just king who was worthy of divine worship. It seems that the Aryan was a language used by the most Iranian people as a formal language of communication. The Rabatak inscription describes events of the first year of Kanishka in words strikingly similar to those used by Dariuš the Great in the inscription of Bisotun. The inscription also names the cities which were under the rule of Kanishka (lines 4-7). It is significant in implying the actual extent of Kushan rule under Kanishka. The inscription will therefore lead to a fundamental reassessment of our understanding of the Kushan kings who ruled an ancient empire centered on the territory now known as Afghanistan Extended Abstracts of the Persian 103 Articles in English and Pakistan. Finally, it is very informative and important that Kanishka mentions the name of the kings who ruled up to his time. They were Kujula Kadphises as his great grandfather, Vima Taktu as his grandfather, Vima Kadphises as his father.